Enhanced 2.5v lvds driver with 1.8v technology for 1.25 ghz performance

Abstract

An enhanced 2.5V LVDS driver with 1.8V technology for 1.25 GHz provides high speed performance for off chip drivers. Level shifting is accomplished in predriver circuits with buffer amplifier circuits operating at the on chip operating voltage level driving differential amplifiers operating at the higher driver circuit operating voltage level. An enhancement circuit is interposed between the level shifting circuits and the output stage, and this enhancement circuit speeds up the switching times of the signals input to the output stage. The enhancement circuit comprises first and second complementary transistors connected in cascode between the higher driver circuit operating voltage and a third transistor connected between the node of a predriver circuit and the higher supply voltage. The gate of the third transistor is connected to a common node between the first and second transistors. A rising signal from the predriver circuit turns the first transistor on causing the third transistor to turn on, pulling the output of the predriver circuit rapidly to the supply voltage. A circuit responsive to the input signal turns off the second transistor preventing current feed through the first and second transistors.